Born as Dean Ward Gilmore in Santa Rosa, California, United States, he worked as sound mixer for 27 years. Gilmore's first credits are the short drama Anatomy of an Accident (1961), the short film Invisible Diplomats (1965), episodes of The Alfred Hitchcock Hour (1965, directed by Joseph Pevney) and Lassie (1966, with Skip Homeier), the science fiction film The Bamboo Saucer (1968), and the drama Chastity (1969).

Further credits include the television thriller Birds of Prey (1973), the comedy I Wonder Who's Killing Her Now? (1975), the drama My Boys Are Good Boys (1978), the action film Good Guys Wear Black (1978, with John B. Schuyler), the action drama Raise the Titanic (1980, with Robert W. Glass, Jr. and Bill Wistrom), the television drama Margin for Murder (1981, with Gordon L. Day), the television series Bret Maverick (1981), the music documentary Cool Cats: 25 Years of Rock 'n' Roll Style (1983, with Andy Nelson), and the television comedy Warm Hearts, Cold Feet (1987).

Gilmore passed away on 9 November 2010 at the age of 84 in San Diego, California, United States.